1. Field of the Invention
The invention is directed to compatibilized polymer blends formed using a multifunctional agent in a polymer blend, preferably consisting of general purpose rubbers and benzyl halide containing polymers.
2. Related Art
Relatively saturated elastomeric polymers, such as butyl rubber, which is a copolymer of isobutylene with a small percentage of isoprene units are known. These polymers demonstrate low air permeability, relatively low glass transition temperatures, broad damping peaks, excellent environmental aging resistance, and other such properties which render these polymers of commercial significance in blends with polymers or in tire production. Butyl rubber generally is incompatible with most other polymers.
It has been known for some time that blends of incompatible polymers can be improved in some cases by adding a suitable compatibilizer so as to alter the morphology of these blends. More particularly, to be successful it has been necessary to reduce the domain sizes for both of the polymers in the blend.
It is known in some instances to use block copolymers as compatibilizers. For example, several studies have shown attempts to compatibilize rubber-rubber blends of polyisoprene and polybutadiene by using diblock materials composed of these two materials. See R. Cohen et al. Macromolecules 15, 370, 1982; Macromolecules 12, 131, 1979; J. Polym. Sci., Polym. Phys. 18, 2148, 1980; J Macromol. Sci.-Phys. B17 (4), 625, 1980. Most of these block copolymers have been previously produced by sequential anionic polymerization processes, which are thus limited to a relatively small number of monomers. It is also known to compatibilize other blends, such as rubber-plastic blends of ethylene-propylene rubber with polypropylene, by using graft copolymers of these two materials. See A. Y Coran et al., U.S. Pat. No. 4,299,931, as well as co-pending commonly assigned applications Ser. No. 07/264,484 now U.S. Pat. No. 4,999,403 and Ser. No. 07/264,485, filed on Oct. 28, 1988.
Others have proposed different solutions for preparing compatibilized blends comprising isoolefin polymers. For example, Wang, in WO 95/09197 describes intervulcanizable blends comprising a mixture of a diolefin polymer or copolymer and a saturated or highly saturated elastomeric copolymer having a number average molecular weight of at least 10,000 and containing from about 0.01 up to about 10 mole % of "Y" functional groups randomly distributed along and pendant to the elastomeric polymer chain, said Y functional groups containing an olefinic or vinyl double bond positioned alpha, beta to a substituent group which activates said double bond towards free radical addition reactions. The preferred activating substituent groups are carboxyl-containing groups, phosphoryl-containing groups, sulfonyl-containing groups, nitrile-containing groups, aromatic ring-containing groups or a combination of such groups.
It would be desirable to obtain a process not employing a solvent. The present invention provides compatibilized blends formed by a solventless reaction between two generally incompatible polymers with a multifunctional compound/agent.